Disk-like cutting tool



A ril 18, 1933. G. F. TAYLOR 1,904,568.

DISK LIKE CUTTING TOOL Filed May 14, 1929 Invehtor: George T. Taylor, bMM s His Attorney.

Patented Apr. 18, 1933 UNITED STATES PATENT OFFICE GEORGE E. TAYLOR, orSCHENECTADY, NEW YORK, ASSIGNOR 'ro GENERAL ELECTRIC COMPANY, ACORPORATION on NEW YORK DISK-LIKE CUTTING TOOL Application filed May 14,

The present invention relates to cutting tools and more particularly tothin disk-like tools made from a sintered hard metal composition whichconsists largely of tungsten-carbide, but contains an appreciable amountof an auxiliar cementing metal having a lower melting point than thecarbide, for example cobalt. A sintered composition of this character,known as cemented carbide, is described in the patentto Schrtiter No.1,549,615 and, in general, consists of a carbide of an element of the6th group of Mendelejefl"s periodic table, for example tungsten-carbideor molybdenum-carbide and a cementing or binder metal of the iron group,such as cobalt. The composition usually contains about 3 to 25% cobaltand preferably about 13% cobalt, the remainder of the composition beingsubstantially tungsten-carbide.

In the copending application of Samuel L. Hoyt, Serial No. 181,536,filed April 6, 1927, now Patent No. 1,843,768, there is disclosed amethod for forming a composition, such as disclosed in the presentapplication, into a dense, hard and tough mass by the simultaneousapplication of heat and pressure to the composition. According to theprior process, the material to be treated is placed in a carbon mold andpressed between carbon plungers While heated to its sintcringtemperature, the pressure applied being approximately 1000 pounds persquare inch.

I have found that when very thin disks of this material, for exampledisks having a thickness of about 1/64", are formed according to theprior process, such disks are somewhat coarse grained and will not takea smooth, sharp edge, for example the edges break or chip easily in thegrinding process.

It is one of the objects of the present invention to provide a disk-likecutting tool of this material having a sharp smooth cutting edge. Suchtools may be employed as glass cutters and like devices. Although I haveillustrated the invention in connection with a glass cutter, it will beclear that the invention is not restricted to that particular type oftool.

In carrying out my invention, I thoroughly mix tungsten-carbide andcobalt in the pro- 1929. Serial No. 363,079.

portion of about 3 to 25% cobalt and about 97 to 75% tungsten-carbide.The powdered materials are placed between relatively soft metal disks,such as molybdenum, which are substantially co-extensive in area withthe cutting disk to be formed. Pressure is applied to the intermediatepowdered materials while they are simultaneously heated to theirsintering temperature. The powdered materials are compacted by thisoperation into a dense thin layer or disk of sintered materialapproximately 1/ 64" in thickness and of extraordinary hardness which iswelded to the outer relatively soft molybdenum disks during the pressingand heating operation.

The composite disk thus formed and comprising a central or intermediatehard, sintered disk and outer relatively soft molybdenum disks may begiven a sharp, smooth edge by grinding or bevellin g the edges of theouter disks and the central disk so that the outer edge of the centraldisk forms the apex of an angle which includes the bevelled edges of theouter disk.

Ordinarily, it would be very difficult to provide a-sintered disk ofthis thickness with a suitable cutting edge owing to its somewhatbrittle nature. When backed up by the relatively soft molybdenumsupporting disks however, this difliculty is overcome and the centraldisk provided with a very sharp, smooth cutting edge.

The novel features which are characteristic of my invention are'setforth with particularity in the appended claims. The invention itselfhowever will best be understood from reference to the followingspecification when considered in connection with the accompanyingdrawing in which Fig. 1 represents a view partly in section and partlyin elevation of an apparatus for forming a composite disk tool, suchas aglass cutter, in accordance with the present invention; Fig. 2 is aperspective view of a glass cutter before the edge portion thereof hasbeen ground, together with a plug adapted to fit in a central opening ofthe tool during the pressing operation; Fig. 3 is a perspective view ofthe composite tool disk with the outer disk slightly removed; Fig. 4 isa view i in elev tion of a: completed: glass cutting;

:;.t0,ol, while Fig. is a cross-sectional view,

z Referring moref part'cularly to 1 portion be mixed with a small amountof water or starch paste and applied to the disk 12, as in my copendingapplication Serial No. 357,536, filed April 23, 1929. The thickness ofthe powdered material 14 on the plate 12 will usually be about fivetimes the thickness desired in the finished product, i. e., if asintered cutting disk 1/64" is desired the powdered material placed onthe disk 12 prior to the application of pressure thereto should beapproximately 5/64" in thickness. The late 12 with the powdered materialthereon is placed in the opening 4 of the mold 1 and plug 5 inserted inthe opening 3 so as to extend through the central opening in the disks.An upper perforated molybdenum disk is then placed on top of thepowdered material and the pressure member 6 inserted in the opening 4 ofthe mold. The mold is then clamped firmly between the cheeks 8 andplaced on a support 16 and under the plunger member 17 of a press.Pressure equal to about 1000 pounds per square inch is applied by thepress to the powdered materials, while the powdered materials aresimultaneously heated to their sintering temperature by means of anelectric current supplied through the electric terminals 10 and 11.

65 A current of about four to five thousand the: drawing, :1 have shownat '1 a rectangus lar "carbon mold having a central: cylindricalopening:extending through the. mold, the. lower part: 3 of the opening being ofrela-" tively small diameter, and the upper part 4 1 of relativelylarge: diameter. and extending imere thanhaltway thrcughithe mold. 9A;refractory; carbon plugfi fills the central openingzi inthemoldj andextends an ap i preciable distanceinto theopening 45.; car-Vbon;plungerjfi fitsintotheopening'd fofthfe i mold and has anopeningltoaceommodatethe carbon plug 5 which slides therein; i'lhe I fmold i is positioned 1 between two: carbon cheeks 8 provided withrig'htangna I open; I .ings:9: therein toaecomm'odate the mold. I A: 1.pair; of electric terminals 16 .andill bear against the cheeks 8; I.Pressure may be upv I plied to theseterm'inals in any suitable man- 1 Ia supporting disk for said sintered dis neeaaee I :minutes heats thepowdered materials to a temperature inthe neighborhood of about i i i E1375"? C. which :is the sinteringtemperature I g l of: the ipbwdlel edmateriaisr 5 The: sirnulta- I neous applicationof pressureand heat tothe I i i l powders produces a very densepr oduet and I i I atthe sametime wel s thepoutenmolyb- I I: denum -plates l2 and :15 to theintermediate ionthe carbon plug 5 prevents expansion: i I

inwardly towards the I I I :sintered disk: I During the pressing operaofthe central disk 14 -centerof thedisk.-f l l l 1 vAfter removal from themold, I I i I Z or bevelled as mdicated in Fig; 4,? the edge j 1 i iedges of the; composite I disk may; be ground 50f the: central :disk;being: ground so: as I to i i l Since, the: particular tool employed toil-' central Opening: through the composite disk I 1 is: fitted with::a; steel rod: 18 which may 9. :driventhroughthe central opening-of I I.I ,trill.openingofthediskaThesteel'rod l8. :i In iearrying ,myinventioninto- 'efieca l Z p i des means-wherebytheglasscutter may I I Iusually; mix: tungsten-carbide Eand cobalt in --i-thspro ertionrof:abeut-;l3%;-cobalt iand. i about :87% timgsteni-carbide and spri nkleit E I over a molybdenum or: other suitable plate ;12;which isrelatively soft: but has arelag tifv ely high 'meltingpoint; plate ispm. I I I vided with a central opening or perforation I 13 I Ifdesired,the powdered material' may diskor, if desired, copper, brazed ini thecert:

disk by the elders, washers 19 may be? fitted on the steel rod or shaft18 so .as to rest a a s e e er y num s es i ;What I c laim'a's new anddesire to securei I g l .by' titers Pa ent of the: United States, is: l1 51b article at manufacture "comprising a pair of metal disks and anintermediate sintered disk consistin largely of a hard metal carbide anda bin er material therefor, said intermediate disk being welded to saidouter disks.

2. Asintered metallic disk consistin largely of a hard metal carbide anda bin er material therefor having a sharp cuttin edge,

said disks being substantially coextensive in area.

3. A sintered disk consisting largely of a hard metal carbide and abinder material therefor having a sharp cutting edge and a supportingdisk welded to said sintered disk, said disks being substantiallycoextensive in area and having aligned openings therethrough for asupporting member.

4. cutting implement comprising two outer disks of relatively soft metaland an intermediate disk of relativel hard material, said intermediatedisk conslstin largely of a hard metal carbide and a bin er materialtherefor, said intermediate disk being reduced in thickness at itsperiphery to thereby provide a cutting edge.

5. A cuttin implement comprising two outer disks 0 relatively softmaterial and an intermediate disk, said intermediate disk consistingsubstantially of a sintered composition o tungsten-carbide and cobaltand foemt e apex of an angle which includesthe I I Z bevelled edges 0fthe-outer disks; i i I I 5 i l f lustrate: my invention; is: a glass:cutter: the I I 1 I having a cutting edge extending beyond said outerdisks.

6. The method of forming a disk-like cutting implement which comprisesplacing powdered materials consisting largely of tungsten but containingappreciable amounts of carbon and cobalt between two substantiallflatand relatively soft metal disks, and app ying pressure to said disksto compress the powdered materials while simultaneous- 1y heating themto their sintering'temperature.

In witness whereof, I have hereunto set my hand this 13th day of May,1929.

15 GEORGE F. TAYLOR.

